Thermal ratchetting deformation of a 316L stainless steel cylindrical structure under an axial moving temperature distribution

Abstract

A study of progressive inelastic deformation under a moving temperature distribution was carried out for a 316L stainless steel cylinder by a structural test and corresponding analysis. This structural test intends to simulate the thermal ratchetting behavior occurring at the thermal liner of a liquid metal reactor as a free surface of a hot sodium pool moves up and down under plant heat-up, cool down conditions and other thermal transients. The thermal ratchetting load of heating the test cylinder up to 550 °C was applied nine times and deformation was measured with one laser displacement sensor and two LVDTs. The temperature distribution of the test cylinder in the axial direction was measured and this was used for the ratchetting analysis. The thermal ratchet deformations were analyzed with the constitutive equation of the non-linear combined hardening model, which was implemented into ABAQUS by means of a UMAT subroutine and the analysis results were compared with those of the test. The residual displacement after nine cycles of the thermal load was measured to be 1.79 mm. The ratchetting deformations obtained by the analysis with the combined hardening model were in reasonable agreement with those of the structural tests. In addition, a case study of the effect of variations of load conditions and geometry conditions on the thermal ratchet was carried out.